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Efficiencies of conversion of some lignocellulosic waste materials by goats
Bioresource Technology 40 (1992) 167-169
Efficiencies of Conversion of Some Lignocellulosic Waste Materials by Goats A. Adeloye Department of Animal Production, University of Ilorin, PMB 1515, Ilorin, Nigeria (Received 20 January 1991; revised version received 15 April 1991; accepted 24 April 1991 )
Abstract
The ability of the goat to utilise some lignocellulosic materials was assessed. Fifteen West African dwarf goats comprising non-pregnant, non-lactating females, intact (uncastrated) males and castrated male goats were involved in digestion and growth studies. The lignocellulosic materials were Leucaena leaf meal, yam peels and cocoa bean shells, together making up 92% of the total diet. The diet had 24% crude protein. Data were collected on DM feed intake, weight grain, nutrient digestibilities and feed/gain ratio. The coefficient of digestibilities of the nutrients were not appreciably different (P> 0"05) between the groups of goats studied. The feed nutrient digestibilities (%) were: dry matter, 56.7; crude protein, 61"7; crude fibre, 30.7, ether extract, 99.6 and nitrogen-free extract, 67.8. The low crude-fibre digestibility was suggested to be due to the source and quality of the dietary fibre. Weight gains were between 122 and 139 g/day and were impressive. The feed conversion was 170g weight gain per kg of feed intake for the female and intact goats, and 200 g weight gain per kg of feed for the castrates. The experimental ration was considered fit for a goat fattening programme. Castration was suggested to obtain a higher efficiency of feed conversion.
man, attention has recently been diverted to crop residues (Adegbola et al., 1988; Alokan, 1988) and agro-industrial by-products (Akinsoyinu & Adeloye, 1987). Yam peel is a crop by-product which is obtained when, the tuber is peeled for food for man. The peel appears tough but light when dry. Cocoa shell is a waste from the cocoa processing industry. It is a dry, crisp, brown shell with a pleasant aroma, separated from the cocoa bean on roasting. Leucaena is a nitrogen-fixing plant whose utilisation as forage for livestock has been suggested (Panesa, 1989). The West African dwarf goat is indigenous to the humid zones of Nigeria and reared for its meat. It is kept at subsistence level by peasants for their immediate financial needs. The goat, being a ruminant animal, is physiologically adapted to digesting coarse plant materials. Particularly significant is its ability to live on lignocellulosic materials where quantity and quality of feeds are low, as occurs in the tropics. There is no information in the literature on the assessment of feeds essentially compounded from these materials, so this study was designed to assess the efficiency of the goat in converting a combination of yam peels, cocoa shells and Leucaena leaf meal to meat.
METHODS
Key words: Goats, lignocellu!osic materials, digestibility, weight gain.
INTRODUCTION In quest of cheaper and lesser known sources of feeding-stuff otherwise not directly utilised by
Fifteen West African dwarf goats about 2 years old and weighing 16-17 kg were fed on a diet made from crop residues (Table 1). The goats were kept in separate pens and maintained on the experimental diet for 42 days during which weight gains and feed intakes were measured. The goats were each fed a daily allowance of 2 kg of the
167 Bioresource Technology 0960-8524/92/S05.00 © 1992 Elsevier Science Publishers Ltd, England. Printed in Great Britain
168
A. Adeloye
experimental ration at 0800 hours. Fresh water was provided daily ad lib. Access to mineralised salt lick was free. At week, 7, three non-pregnant, non-lactating females, three intact (uncastrated) bucks and three castrated bucks were weighed and transferred to individual metabolism cages for the collection of faeces. The animals had a 7-day adjustment period in the cages followed by a 7-day period of collection of faeces. Faeces voided were weighed daffy and dried to constant weight at 63°C. The dried samples were weighed, bulked, milled and preserved in air-tight plastic bottles for chemical analysis. The animals were weighed weekly. The experimental ration and the faeces were analysed for the chemical components by the AOAC (1975) methods. The dry matter (DM)
Table 1. Composition of the experimental diet
Ingredient Yam peel Cocoa bean testa Leucaena leaf meal Groundnut cake Urea Salt (NaCI) Di-calcium phosphate
Composition (%) 26 36 30 6 1 0-5 0.5 100
Analysed composition Dry matter
91.3
On dry matter basis Crude protein Crude fibre Ether extract Total ash Energy (kcal/g DM)
23-7 16.1 5"8 7-9 4-3
feed intakes, body weight gains and the gain: feed ratios were statistically analysed (Steel & Torrie, 1980) and means tested (Duncan, 1955). RESULTS AND DISCUSSION The
proximate
analyses indicated that
rich in total nitrogen. It was therefore included in the ration as a principal source of nitrogen. The inclusion of the Leucaena leaf meal at less than 40% of the total ration (Librojo & Hatchcock, 1974; Glasby, 1975) was due to its content of the toxic amino acid mimosine (Blood et al., 1979; Liener, 1980). The cocoa shell and yam peel served as sources of energy. They were maintained at the percentage levels indicated (Table 1) with due regard to their energy and crude protein contents, bearing in mind the need to obtain the highest possible level of crude protein in ihe total ration. The composition of the experimental diet is presented in Table 1. The lignocellulosic materials altogether made up 92% of the total experimental diet. Summaries of the DM feed intake, weight gain and efficiency of feed conversion by the goats are presented in Table 2. Daily DM intakes in all the groups of goats were of the order of 0"7 kg. When expressed as a percentage of live weight, the daily DM consumed by the female and intact bucks were significantly higher (P<0.05) than those of the castrated bucks. However, the physiologically normal goats had lower (P< 0-05) weight gains than the castrates. The castrates had a higher (P< 0-05) feed conversion efficiency (200 g weight gain per kg of feed) than the normal goats. Sex difference was not appreciable as indicated by
Table 2. Summaries of feed intake, weight gain and efficiency of feed conversion by the goat
Female
Experimental period (days) Mean initial liveweight (kg) Mean final liveweight (kg) Mean weight gain (kg) Daily gain (g) Dry matter (DM) intake (g/day) DM intake (% of liveweight) Efficiency of feed conversion (gain/feed ratio)
the
Leucaena leaf meal (28.8% crude protein) is very
56 12-27 19-10 6"83 121.96 b 717.22 4.57" 0.17 h
Male h~tact
Castrated
56 12.47 19.41 6.94 123"93 b 717.67 4.50" 0.17 b
56 13.96 21.73 7.77 138-75 u 706"33 4-0 b 0.20 u
"'hValues on the same row with the same superscript are not statistically different (P> 0-05).
Conversion of lignocellulosic waste materials by goats
uniformity (P>0.05) in feed conversion efficiency, growth rate and DM intake values of the normal male and female animals. The observed variations in all the groups for the digestibility coefficients of dry matter, crude protein, crude fibre, ether extract and nitrogenfree extract were not significant (P>0.05). The effects of castration could therefore have been manifest in a higher efficiency of conversion of the feed to body tissues. A general observation of the coefficients of digestibilities showed that the dry matter was fairly digested (56"7%), the crude protein (61.7%) and nitrogen-free extracts (67.8%) were well digested, while ether extract (99"6%) was very well digested. However, the digestibility of crude fibre was low (30"7%). The level of the dietary fibre could not be implicated for the poor digestibility of the crude fibre as a control diet in a comparable study by Alokan (1988) contained 17.5% crude fibre and the 80% digested. Absence of readilyavailable nitrogen could not be the cause as nitrogen was easily available in the ration (Table 1). However, lignin has been known to affect the digestibility of fibre. Of the total ration, 92% was of plant origin. So, the low digestibility of the crude fibre could be attributed to the sources, and therefore the quality, of the dietary fibre. The gains in weight were impressive, as the figures were higher than some reported values (Alokan, 1988) for sheep and compared well with others (Adegbola et al., 1988) for goats. The experimental ration could therefore be suitable as a production ration for the goat, especially in a
169
fattening programme. In this case, the use of castrates would produce better results in terms of weight gains. REFERENCES Adegbola, T. A., Ogbona, R. C. & Nwachukwu, N. E. (1988). Nutrient intake, digestibility and rumen studies in goats fed varying levels of cassava peels and brewer's dried grain. Nigerian Journal of Animal Production, 15, 161-6. Akinsoyinu, A. O. & Adeloye, A. A. (1987). Studies on the utilisation of cocoa ( Theobroma cacao, L.) seed shells by sheep and goats in Nigeria. Paper presented on Efficient Utilisation of Cocoa By-products, 10th International Cocoa Research Conference, San Francisco, CA, February 1987. Alokan, J. A. (1988). A note on corn cobs in sheep diet. Nigerian Journal of Animal Production, 15, 227-31. AOAC (1975). Official Methods of Analysis, 12th edn. Association of Official Analytical Chemists, Washington, DC. Blood, D. C., Henderson, J. A. & Radiostitis, O. M. (1979). Trees and shrubs. In Veterinary Medicine, 5th edn. Cassel, London, p. 1018. Duncan, D. B. (1955). Multiple range and multiple F-tests. Biometrics, 11, 1-42. Glasby, J. (1975). Encyclopaedia of the Alkaloids. Plenum Press, New York, London, I, p. 189; I1, p. 966. Librojo, N. T. & Hatchcock, J. N. (1974). Metabolism of mimosine and other compounds from Leucaena leucocephala by chicken. Nutrition Reports International, 9, 217-22. Liener, I. E. (1980). Mimosine. In Toxic Constituents of Plant Foodstuffs, 2nd edn., ed. J. L. Howard. W. B. Saunders, Philadelphia, PA, pp: 437-8. Panesa (1989). Pasture network for eastern and southern Africa. International Livestock Centre for Africa, Addis Ababa, Ethiopia, No. 9, pp. 6-7. Steel, R. G. D. & Torrie, J. H. (1980). Principles and Procedures of Statistics. A Biometrical Approach, 2nd edn. McGraw-Hill, New York.
Efficiencies of Conversion of Some Lignocellulosic Waste Materials by Goats A. Adeloye Department of Animal Production, University of Ilorin, PMB 1515, Ilorin, Nigeria (Received 20 January 1991; revised version received 15 April 1991; accepted 24 April 1991 )
Abstract
The ability of the goat to utilise some lignocellulosic materials was assessed. Fifteen West African dwarf goats comprising non-pregnant, non-lactating females, intact (uncastrated) males and castrated male goats were involved in digestion and growth studies. The lignocellulosic materials were Leucaena leaf meal, yam peels and cocoa bean shells, together making up 92% of the total diet. The diet had 24% crude protein. Data were collected on DM feed intake, weight grain, nutrient digestibilities and feed/gain ratio. The coefficient of digestibilities of the nutrients were not appreciably different (P> 0"05) between the groups of goats studied. The feed nutrient digestibilities (%) were: dry matter, 56.7; crude protein, 61"7; crude fibre, 30.7, ether extract, 99.6 and nitrogen-free extract, 67.8. The low crude-fibre digestibility was suggested to be due to the source and quality of the dietary fibre. Weight gains were between 122 and 139 g/day and were impressive. The feed conversion was 170g weight gain per kg of feed intake for the female and intact goats, and 200 g weight gain per kg of feed for the castrates. The experimental ration was considered fit for a goat fattening programme. Castration was suggested to obtain a higher efficiency of feed conversion.
man, attention has recently been diverted to crop residues (Adegbola et al., 1988; Alokan, 1988) and agro-industrial by-products (Akinsoyinu & Adeloye, 1987). Yam peel is a crop by-product which is obtained when, the tuber is peeled for food for man. The peel appears tough but light when dry. Cocoa shell is a waste from the cocoa processing industry. It is a dry, crisp, brown shell with a pleasant aroma, separated from the cocoa bean on roasting. Leucaena is a nitrogen-fixing plant whose utilisation as forage for livestock has been suggested (Panesa, 1989). The West African dwarf goat is indigenous to the humid zones of Nigeria and reared for its meat. It is kept at subsistence level by peasants for their immediate financial needs. The goat, being a ruminant animal, is physiologically adapted to digesting coarse plant materials. Particularly significant is its ability to live on lignocellulosic materials where quantity and quality of feeds are low, as occurs in the tropics. There is no information in the literature on the assessment of feeds essentially compounded from these materials, so this study was designed to assess the efficiency of the goat in converting a combination of yam peels, cocoa shells and Leucaena leaf meal to meat.
METHODS
Key words: Goats, lignocellu!osic materials, digestibility, weight gain.
INTRODUCTION In quest of cheaper and lesser known sources of feeding-stuff otherwise not directly utilised by
Fifteen West African dwarf goats about 2 years old and weighing 16-17 kg were fed on a diet made from crop residues (Table 1). The goats were kept in separate pens and maintained on the experimental diet for 42 days during which weight gains and feed intakes were measured. The goats were each fed a daily allowance of 2 kg of the
167 Bioresource Technology 0960-8524/92/S05.00 © 1992 Elsevier Science Publishers Ltd, England. Printed in Great Britain
168
A. Adeloye
experimental ration at 0800 hours. Fresh water was provided daily ad lib. Access to mineralised salt lick was free. At week, 7, three non-pregnant, non-lactating females, three intact (uncastrated) bucks and three castrated bucks were weighed and transferred to individual metabolism cages for the collection of faeces. The animals had a 7-day adjustment period in the cages followed by a 7-day period of collection of faeces. Faeces voided were weighed daffy and dried to constant weight at 63°C. The dried samples were weighed, bulked, milled and preserved in air-tight plastic bottles for chemical analysis. The animals were weighed weekly. The experimental ration and the faeces were analysed for the chemical components by the AOAC (1975) methods. The dry matter (DM)
Table 1. Composition of the experimental diet
Ingredient Yam peel Cocoa bean testa Leucaena leaf meal Groundnut cake Urea Salt (NaCI) Di-calcium phosphate
Composition (%) 26 36 30 6 1 0-5 0.5 100
Analysed composition Dry matter
91.3
On dry matter basis Crude protein Crude fibre Ether extract Total ash Energy (kcal/g DM)
23-7 16.1 5"8 7-9 4-3
feed intakes, body weight gains and the gain: feed ratios were statistically analysed (Steel & Torrie, 1980) and means tested (Duncan, 1955). RESULTS AND DISCUSSION The
proximate
analyses indicated that
rich in total nitrogen. It was therefore included in the ration as a principal source of nitrogen. The inclusion of the Leucaena leaf meal at less than 40% of the total ration (Librojo & Hatchcock, 1974; Glasby, 1975) was due to its content of the toxic amino acid mimosine (Blood et al., 1979; Liener, 1980). The cocoa shell and yam peel served as sources of energy. They were maintained at the percentage levels indicated (Table 1) with due regard to their energy and crude protein contents, bearing in mind the need to obtain the highest possible level of crude protein in ihe total ration. The composition of the experimental diet is presented in Table 1. The lignocellulosic materials altogether made up 92% of the total experimental diet. Summaries of the DM feed intake, weight gain and efficiency of feed conversion by the goats are presented in Table 2. Daily DM intakes in all the groups of goats were of the order of 0"7 kg. When expressed as a percentage of live weight, the daily DM consumed by the female and intact bucks were significantly higher (P<0.05) than those of the castrated bucks. However, the physiologically normal goats had lower (P< 0-05) weight gains than the castrates. The castrates had a higher (P< 0-05) feed conversion efficiency (200 g weight gain per kg of feed) than the normal goats. Sex difference was not appreciable as indicated by
Table 2. Summaries of feed intake, weight gain and efficiency of feed conversion by the goat
Female
Experimental period (days) Mean initial liveweight (kg) Mean final liveweight (kg) Mean weight gain (kg) Daily gain (g) Dry matter (DM) intake (g/day) DM intake (% of liveweight) Efficiency of feed conversion (gain/feed ratio)
the
Leucaena leaf meal (28.8% crude protein) is very
56 12-27 19-10 6"83 121.96 b 717.22 4.57" 0.17 h
Male h~tact
Castrated
56 12.47 19.41 6.94 123"93 b 717.67 4.50" 0.17 b
56 13.96 21.73 7.77 138-75 u 706"33 4-0 b 0.20 u
"'hValues on the same row with the same superscript are not statistically different (P> 0-05).
Conversion of lignocellulosic waste materials by goats
uniformity (P>0.05) in feed conversion efficiency, growth rate and DM intake values of the normal male and female animals. The observed variations in all the groups for the digestibility coefficients of dry matter, crude protein, crude fibre, ether extract and nitrogenfree extract were not significant (P>0.05). The effects of castration could therefore have been manifest in a higher efficiency of conversion of the feed to body tissues. A general observation of the coefficients of digestibilities showed that the dry matter was fairly digested (56"7%), the crude protein (61.7%) and nitrogen-free extracts (67.8%) were well digested, while ether extract (99"6%) was very well digested. However, the digestibility of crude fibre was low (30"7%). The level of the dietary fibre could not be implicated for the poor digestibility of the crude fibre as a control diet in a comparable study by Alokan (1988) contained 17.5% crude fibre and the 80% digested. Absence of readilyavailable nitrogen could not be the cause as nitrogen was easily available in the ration (Table 1). However, lignin has been known to affect the digestibility of fibre. Of the total ration, 92% was of plant origin. So, the low digestibility of the crude fibre could be attributed to the sources, and therefore the quality, of the dietary fibre. The gains in weight were impressive, as the figures were higher than some reported values (Alokan, 1988) for sheep and compared well with others (Adegbola et al., 1988) for goats. The experimental ration could therefore be suitable as a production ration for the goat, especially in a
169
fattening programme. In this case, the use of castrates would produce better results in terms of weight gains. REFERENCES Adegbola, T. A., Ogbona, R. C. & Nwachukwu, N. E. (1988). Nutrient intake, digestibility and rumen studies in goats fed varying levels of cassava peels and brewer's dried grain. Nigerian Journal of Animal Production, 15, 161-6. Akinsoyinu, A. O. & Adeloye, A. A. (1987). Studies on the utilisation of cocoa ( Theobroma cacao, L.) seed shells by sheep and goats in Nigeria. Paper presented on Efficient Utilisation of Cocoa By-products, 10th International Cocoa Research Conference, San Francisco, CA, February 1987. Alokan, J. A. (1988). A note on corn cobs in sheep diet. Nigerian Journal of Animal Production, 15, 227-31. AOAC (1975). Official Methods of Analysis, 12th edn. Association of Official Analytical Chemists, Washington, DC. Blood, D. C., Henderson, J. A. & Radiostitis, O. M. (1979). Trees and shrubs. In Veterinary Medicine, 5th edn. Cassel, London, p. 1018. Duncan, D. B. (1955). Multiple range and multiple F-tests. Biometrics, 11, 1-42. Glasby, J. (1975). Encyclopaedia of the Alkaloids. Plenum Press, New York, London, I, p. 189; I1, p. 966. Librojo, N. T. & Hatchcock, J. N. (1974). Metabolism of mimosine and other compounds from Leucaena leucocephala by chicken. Nutrition Reports International, 9, 217-22. Liener, I. E. (1980). Mimosine. In Toxic Constituents of Plant Foodstuffs, 2nd edn., ed. J. L. Howard. W. B. Saunders, Philadelphia, PA, pp: 437-8. Panesa (1989). Pasture network for eastern and southern Africa. International Livestock Centre for Africa, Addis Ababa, Ethiopia, No. 9, pp. 6-7. Steel, R. G. D. & Torrie, J. H. (1980). Principles and Procedures of Statistics. A Biometrical Approach, 2nd edn. McGraw-Hill, New York.